[TYPO3] Can I change the icon in the backend's page tree based on a flag?

[Dobes Vandermeer]

I have a plugin which lets me attach a flag to a page.  I'd like to show  
visually which pages have this flag set, and which don't, by modifying the  
icon for the page, hopefully by adding a little "badge" like the way that  
links work.

Is this possible?  I'm a bit of a newbie but I seem to have narrowed the  
icon creation/selection down to t3lib_iconWorks::getIcon().  Here it  
calculates the icon to use, but there doesn't seem to be any hooks for an  
extension to modify the icon.  It seems to have a hardcoded list of flags  
that are used to determine the unique identity of the icon, which later  
determine the icon style and overlays:

($hidden || $timing || $futuretiming || $user || $deleted || $shaded ||  
$noIconFound)

It looks like I'd have to add another flag, adjust $string and $flags, and  
also change makeIcon() to detect the new type and add the correct  
overlay.  Unfortunately, I want to do this in an extension, not by  
modifying the core code.

Is there any hope for me?

Thanks,
Dobes